scope:

This guideline is intended for diagnostic test manufacturers, external quality control and proficiency testing providers, and regulatory agencies. Although clinical laboratory use will probably be limited because of the complexity of the calculations, the observations and conclusions should be useful to all professionals. The guideline provides protocols that evaluate matrix effects in processed samples that are used as standards, calibrators, controls, and EQA/PT materials.

EP14 will assist in the education of clinical laboratorians, regulators, diagnostic manufacturers, and the public about the impact of matrix effects on the assessment of the quality of laboratory performance. For example, readers are warned that matrix effects, caused by the interaction of processed material and the measurement procedure, may suggest that erroneous results are being generated when in fact the results are acceptable. Conversely, "acceptable" control results may also give a false sense of confidence that procedures are performing adequately. Terms and concepts used to report these and related issues are defined within this document.

This guideline can be used by laboratorians performing quantitative tests for a wide variety of analytes across various disciplines. The testing protocols attempt to accommodate situations where reference methods do not exist.

The protocols help laboratorians distinguish between effects caused by measurement procedure malfunctions and those caused by use of processed samples. However, the protocols do not describe approaches that specifically establish the exact mechanism of the matrix effect(s).

By following the protocols, manufacturers and EQA/PT providers should be able to provide some documentation to government or accrediting agencies on matrix effects to help avoid false conclusions about the adequacy of patient testing.